I have the same issue. I completed the game but it plagued me the whole time. I have a solid smooth 60fps on a 60hz monitor but the game is very choppy after a few minutes of play then in gets worse quickly. frames never drop whatsoever but it is just sickeningly choppy. i7 3820 3.6ghz, 16gb ram, gtx 970, win10 64bit. In seeing this issue in certain games over the years it always seems like some kind of vsync issue or something to do with frame skipping/frame stutter/whatever it would be called. Some games have it badly, like Destiny 2. Most every other game I play though does not have this problem. I'm glad it's just not an issue with me as I suspected it wasn't. I've tried settings graphics to low, high, custom, borderless window, borderless fullscreen, turning off vsync in-game and forcing it through nvidia control panel, turned on triple buffering, basically things like that. No luck. I would just like to play the end game content in peace but the frame skipping/stuttering/chopping is sickeningly bad.